Relation of Weather to Crops 93 



the above date the larger ones were nearly all killed to the ground, 

 and the smaller ones considerably injured, the mercury falling to 

 26° at the ground, 30° in the government shelter, and 35° at the 

 Weather B ureau. Potatoes that were planted February 22, and were 

 just coming up, were very slightly injured. 



During five years' observations potatoes planted during Febru- 

 ary have received no serious injury from frost, although some plants 

 have been slightly injured each year. During April, potatoes that 

 started in February or early March grow rapidly and early varieties 

 begin forming tubers. Thrifty growth continues throughout most 

 of May, if no unusually warm weather occurs. In 1902 an unsea- 

 sonably warm period occurred between May 6 and 10, the maximum 

 temperatures being 108° to 110° at the soil each day, and 99° in the 

 government shelter, and the mean relative humidity but 20. Pota- 

 toes planted January 20 and February 4 that were blossoming were 

 considerably injured, and the crop was much lighter that year than 

 usual. vSome injury was also done May 12 and 13, 1903, when the 

 maximum temperatures in the government shelter were 102° and 

 106°, respectively. 



The increasing heat and aridity of June hasten the maturity 

 or death of all potato tops, regardless of when they were planted or 

 what the variety may be. Only early varieties have sufficient time 

 to come to maturity before being overcome by the heat. The 

 varieties that are grown most successfully in the region are Early 

 Rose, Triumph, and Burpee's Extra Early. These varieties usually 

 mature about the middle of June, although a large share of the 

 ■crop is often dug and marketed considerably earlier than this. 

 On account of the weather, the tubers deteriorate rapidly after 

 ripening, whether dug or left in the ground. For this reason, by 

 July 4 all the crop of the season is ordinarily consumed, except a 

 small amount that a few growers save as best they can for summer 

 planting. 



From seed saved from the spring crop, a few potatoes are grown 

 during autumn. They are planted during August or early Septem- 

 ber, and as a precaution against decay, are not cut. The sprouts 

 sent up are usually distinctly slender and the subsequent growth 

 is of the same character. As the cooler weather of autumn comes, 

 they grow somewhat more rapidly, and produce a small crop of 

 tubers. They do not usually have time for full maturity before the 

 frosts of late autumn. In 1899 they were partly killed December 2, 

 when the ground minimum temperature was 26°, in the government 

 shelter 32°, and at the weather Bureau 38°, and were entirely killed 



